ML20035C673
| ML20035C673 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 04/02/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20035C672 | List: |
| References | |
| NUDOCS 9304080283 | |
| Download: ML20035C673 (3) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0.
TO FACILITY OPERATING LICENSE NO. OPR-35 ILOSTON EDISON COMPANY PILGRIM NUCLEAR F0WER STATION DOCKET NO. 50-293
1.0 INTRODUCTION
By letter dated August 17, 1992, as supplemented by information provided on i
January 22, 1993, and February 1, 1993, the Boston Edison Company (BEco/the licensee) submitted a request for changes to the Pilgrim Nuclear Power Station, Technical Specifications (TS).
The requested changes would change the control circuits for several valves in the high pressure coolant injection (HPCI) system.
Primarily, the proposed amendment would replace the HPCI steam line low pressure (100>P>50 psig) signal for HPCI system isolation and HPCI turbine trip with the reactor low pressure (100>P>50 psig) signal.
The proposed amendment would also provide position indication of the associated HPCI valves in the control room in compliance with the recommendations of Regulatory Guide 1.97.
This change request covers incorporation of these changes in the Pilgrim Technical Specification (TS) Tables 3.2.8 and 4.2.B.
The supplemental information, provided clarifying information that did not change the initial proposed no significant hazards consideration determination.
2.0 BACKGROUND
In a related modification, the licensee is replacing two turbine exhaust drain isolation valves, CV-9068A and CV-9068B to meet the recommendations of Regulatory Guide 1.97 for position indication in the control room.
During this changeout, the licensee proposes to provide similar control room indication for the following HPCI valves:
M02301-4 HPCI steam to turbine M02301-5 HPCI steam to turbine M02301-35 HPCI pump suction from Torus M02301-36 HPCI pump suction from Torus M02301-14 HPCI miniflow bypass to Torus Most of the HPCI equipment is located in the reactor building. The steam supply for the HPCI turbine is piped from a main steam header in the primary containment. At present, four low pressure switches (PS 2387A, B, C and D) located on the HPCI steam lira inside the containment are used to isolate the HPCI isolation valves and trip the HPCI turbine on low steam pressure.
This isolation is provided to ensure that radioactive steam and gases will not 9304080283 930402 PDR ADOCK 05000293 P
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escape from the HPCI turbine shaft seals into the reactor building when steam pressure is too low.
The isolation setpoint is chosen at a pressure below which the HPCI turbine cannot operate effectively.
Currently, low reactor pressure is sensed by four pressure transmitters which are mounted on instrument racks outside the drywell.
The transmitters provide electrical signals to analog trip units located in the cable spreading room. The tripping of either the "A" or "B" division of these trip units initiates isolation of the HPCI turbine exhaust vacuum breaker line.
The isolation setpoint of this system is set at the same setpoint as the HPCI steam line low pressure isolation signal.
The proposed amendment would replace the HPCI steam line low pressure signal with the reactor low pressure signal.
3.0 EVALVATION The current logic associated with the HPCI steam line low pressure signal is one-out-of-two taken twice for a single channel.
The logic associated with the reactor low pressure signal is a two-out-of-two taken once for two channels.
Thus, the proposed isolation logic is single failure proof while the existing logic is vulnerable to single failure because it is using only one train.
The existing HPCI steam line low pressure switches are located inside the primary containment close to the reactor vessel steam dome.
There is a large steam pipe between the steam dome and the HPCI steam line low pressure switches. As indicated in the Final Safety Analysis Report (FSAR), the pressure drop from the reactor vessel steam dome to the HPCI turbine inlet would not exceed 10 psig. Moreover, the HPCI steam line low pressure switches and the reactor vessel low pressure switches are located in close proximity and, therefore, the differential pressure between them will be much less.
Furthermore, the HPCI steam line low pressure switches are located in a high radiation area where plant personnel are vulnerable to radiation exposure during maintenance, surveillance, and calibration tests. On the other hand, most of the maintenance, surveillance, and calibration tests on the reactor low pressure switches and the associated analog trip units can be performed in a low radiation area. The licensee proposes to remove the four HPCI steam line low pressure switches permanently. This will save on man-hours required for maintenance of these pressure switches and will reduce radiation exposure.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Massachusetts State Official was notified of the proposed issuance of the amendment. The State official had no comments.
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5.0 ENVIRONMENTAL CONSIDERATION
j The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.
The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (57 FR 61107). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
6.0 CONCLUSION
Based on the above evaluation, the staff concludes that the proposed changes will improve the HPCI system isolation reliability in accordance with the single failure criterion and the guideline of Regulatory Guide 1.97, and are therefore, acceptable.
The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
F. Paulitz/B. Marcus Date:
April 2. 1993 i
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